"There's a wide range of benefits that are claimed to come from animals and I'm sure that the benefits are there, but under what circumstances and how we can capitalise on them for the welfare of the community we don't quite know," she said.

"There are a number of biological indices we can measure along with a number of psychological measures as well as asking people, which is also part of science."

At the Queen Elizabeth Hospital in Adelaide, a labrador Nilfisk visits patients regularly and dog handler Marie Dow says they clearly are pleased to see him.

"You walk in with him and their faces light up and it immediately starts a conversation and often people will reminisce about dogs they've had in the past," she said.

The researchers say a better understanding would allow guidelines to be developed for support groups and healthcare professionals.